1. Field of the Invention
The present invention relates to a perpendicular magnetic write head provided with a magnetic pole and a side shield layer, and a method of manufacturing the same.
2. Description of the Related Art
In recent years, it is required to improve the performance of a magnetic write head because of the increasing writing density of a magnetic recording medium such as a hard disk (hereinafter referred to as “recording medium”). Accordingly, a perpendicular magnetic write head in which a signal magnetic field is set in a direction perpendicular to a recording surface of the recording medium attracts attention. This is because the advantages that a linear recording density becomes high, and that data written into the recording medium is less affected by the influence of heat fluctuation are obtained.
The perpendicular magnetic write head is provided with a thin film coil that generates a magnetic flux, and so on, together with a main magnetic pole layer. The main magnetic pole layer includes a tip part (magnetic pole) of a microscopic width that generates a writing magnetic field (perpendicular magnetic field). These days, it is also under review to provide a side shield layer adjacently to the magnetic pole in a writing track width direction via a gap layer, in order to achieve higher recording density by suppressing the generation of side-track erasure.
As for a method of manufacturing such perpendicular magnetic write head, a method of forming a side shield layer with a photolithography method and an etching method is proposed (for example, see Japanese Patent Application Publication No. 2007-257711). In this method, after forming a non-magnetic layer at first, a photoresist pattern is formed on the non-magnetic layer by means of a photolithography method. Subsequently, the non-magnetic layer is etched with the photoresist pattern as a mask to form a narrow opening portion and a wide opening portion located separately therefrom. Finally, a magnetic pole and a side shield layer are formed, at a time, in the narrow opening portion and the wide opening portion respectively.
Here, in the perpendicular magnetic write head provided with the side shield layer, a gap (side gap) between the magnetic pole and the side shield layer has a big influence on the writing performance. It is because the quantity of magnetic flux taken into the side shield layer varies depending on the size of the side gap. Thus it is required that the thickness of the side gap be formed as narrow as possible and be strictly controlled in order to be more adaptable to the further improving high recording density.
However, in the existing method of manufacturing the perpendicular magnetic write head, the length of the side gap is affected by the resolution of photolithography method. In this case, since there is a limitation in a patterning width, the length of the side gap is also limited naturally. Moreover, since the actual length of the side gap is determined by the accuracy of the etching, the length of the side gap varies due to the error of the etching amount and so on.